Plastic modular link conveyor belts are ideally suited for processing foods, chemicals and other critical products that must be protected from environmental contamination, such as bacteria, oil or accumulated dust, dirt and grime. In such environments the belt and belt drive systems need to be sanitized or cleaned frequently, and this is difficult and possibly dangerous when the drive system is located inaccessibly. Also, conventional drive systems using sprocket teeth often employ rough surfaces, crevices and corners tending to accumulate contaminants. In such environmental operating conditions, it has been difficult with prior art systems to meet the critical requirements for cleanliness and sanitation because of the presence of sprocket drive teeth and accompanying drive mechanisms in modular link belt drive systems. Consider that because of the mechanical requirements to bear loads and to rotate for long times sprocket gear teeth and accompanying drive mechanisms require lubrication, which encourages vapors and grime inconsistent with sanitation and lack of contamination. Thus, it is a significant problem when contaminants are present, even in trace quantities and where sprockets and drive systems take configurations that tend to breed pockets of contaminants and which are very difficult to reach and clean.
Furthermore sprocket drive systems often employ mechanisms which are subject to excessive wear in the environment of modular link belt operations, where abrasive residue from the belt can significantly shorten operating life.
Additionally safety to operating and service personnel is a problem. However, conventional prior art sprocket drive mechanisms for conveyor belts have drive gears, pulleys and like mechanisms which may not be adequately protected from the possibility of encounter with clothing, tools, loads or even personal body parts such as hands which can be damaged or eyes into which damaging materials could be thrown.
Sprocket drive systems having multiple sprockets across the width of a belt that are rigidly spaced tend to interfere with a modular conveyor belt under conditions of stress, curves and changes of dimensions in mating belt drive socket configurations because of loading or temperature changes. Also as a matter of quality control, it may be difficult to keep modular conveyor belt configurations within very exacting dimensional tolerances that fit fixed sprocket drive wheel spacings. As emphasized when metal drive sprockets engage plastic belt modules, the undesired friction and loading is accompanied by belt wear that significantly reduces belt life.
Furthermore, the location of belt drive sprockets in belt drive systems may not be optimal because of the power drive trains that heretofore have not been compact to fit in various limited space positions. Also it is desirable for optimal system performance to distribute drive power to various belt locations, particularly with longer belts, and the inconvenience of coordinating power drive systems for this purpose has led to compromise in system performance and operating life. Nor have the power drive systems been accessible for maintenance and replacement of defective or worn sprocket wheels and the like, thereby introducing complexity and labor cost for disassembly of portions of the conveyor system to service the power drive portion.
It is therefore an objective of this invention to provide improved sprocket drive systems in modular conveyor belt systems.
Another object of the invention is to provide sprocket drive systems with longer operating life.
Still another object is to provide sprocket drive systems with improved safety to operating and service personnel.
Further it is an object of the invention to produce sprocket to belt drive configurations that are less susceptible to interference when encountering stress and dimensional variations in the conveyor belts.
Another objective of the invention is to provide compact modular drive units that are substantially universally positionable along a conveyor belt system, and adaptable to different belt design and drive sprocket configurations.
Other objects, features and objectives of the invention will be found throughout the following description, drawings and claims.